Heat shrinkable tubing has been used for a number of years to replace tape and other tediuous means for protecting splices in cable and repair of pipe, etc. Commonly, the splice to be insulated or the pipe or cable to be covered is cut to permit the tube to be slipped over one segment followed by rejoining the cable or pipe, then slipping the heat shrinkable tube over the repair or splice. In many cases, however, it is not practical to slide a preformed tube over the splice or repair, it is useful to have a heat shrinkable member formed into a tube having an open longitudinal seam. Such a tube can be slipped around an existing splice or section of pipe or cable to be repaired eliminating the need to cut the cable in order to place the protective covering over it.
Heart shrinkable articles having such a tubular form have been disclosed in the literature as shown in U.S. Pat. No. 3,379,218. The method of closing the tube seam heretofore has consisted of some mechanical closure such as a metal rail, buttons, clamps, etc., to keep the fwo faces of the tube together during the heat shrinking process. A rigid mechanical closure has heretofore been found to be necessary because of the very high shear forces acting on the two ends which are held together during shrinking. While these mechanical closures have been successful in preventing the two edges from coming apart during heat recovery, they result in a bulky closure whose cross sectional area is much greater than wall thickness of the heat recoverable member. Therefore, during the heat shrinking or recovery process the wall of the tube becomes much hotter than the mechanical closure resulting in greater stress on the wall of the item during recovery which can lead to a split in the recovering portion. In order to simplify the closure system and avoid the disadvantages of mechanical closing means noted above, the employment of adhesives to bond the two ends of the closure sheet together has been described as in U.S. Pat. No. 3,770,556 and U.S. Pat. No. 3,959,052. So far as is known, closures of the type described in the first of the above two patents have not seen commercial use, presumably because adhesive bonds of the type described have not been sufficiently strong. The closure method described in the second of the above two noted patents has been in commercial use and provides a completely satisfactory closure. This method requires the use of lower alkyl-alpha-cyanoacrylate adhesives. These adhesives form bonds of enormous strength and result in finished closures which are entirely satisfactory. These adhesives, however, are chemically reactive and very quick setting. The adhesives must, however, be employed in the field, frequently under awkward working conditions and some users of such closures have been reluctant to make use of the cyanoacrylate adhesives because they must be handled with care if injury to personnel is to be avoided.
It is the object of the present invention to provide an adhesive means of sealing two edges of a heat shrinkable or recoverable article to form a tubular member around the item on which the member is being shrunk for purposes of repairing leaks, sealing splices or cable junctions which does not require field use of an adhesive which presents any hazard to personnel.